1. Field of the Invention
The present invention relates to a rotary sheet- or web-fed printing machine for making multicolor prints, notably for printing safety backgrounds of paper currency, for instance banknotes, of the type comprising essentially an impression cylinder around which the paper to be printed is caused to pass, a first blanket cylinder, at least two plate cylinders each inked with a different color by a separate inking device and cooperating with said blanket cylinder for applying a multicolor image to this blanket cylinder, a group of two cylinders comprising a plate cylinder to which a typographic plate representing the complete design to be printed is affixed, and a second blanket cylinder contacting said plate cylinder.
2. The Prior Art
A machine of this character has been proposed for printing an image with juxtaposed colors by means of a single printing plate and a plurality of inking rollers, this method being usually referred to as the "Orlof" method.
In this method, a cylinder carrying a single typographic plate representing the complete design to be printed is used. This plate is inked by a collector cylinder inked in turn by sectioned inking rollers each adapted to transfer the color received from its particular inking device. With this method a multicolor image characterized by a perfect register between the different colors of design is obtained, a result unattainable with any other printing method.
On the other hand, the superposed color and design printing is also known (indirect typography or offset) which is likewise frequently used for printing safety backgrounds of paper currency. In this method, the complete design is composed of partial designs of different colors carried by printing plates wrapped around plate cylinders to permit the superposition of perfectly registering designs and colors. The number of printing plates and consequently of plate cylinders corresponds to the number of different colors and designs constituting the multicolor image.
In the present state of the art, machines utilizing separately one or the other of the above-mentioned methods have been developed.